btrfs: ctree: Reduce one indent level for btrfs_search_old_slot()

Similar to btrfs_search_slot() done in previous patch, make a shortcut
for the level 0 case and allow to reduce indentation for the remaining
case.
Reviewed-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
[ update changelog ]
Signed-off-by: David Sterba <dsterba@suse.com>

fs/btrfs/ctree.c

@@ -3005,6 +3005,8 @@ int btrfs_search_old_slot(struct btrfs_root *root, const struct btrfs_key *key,
 	p->locks[level] = BTRFS_READ_LOCK;
 
 	while (b) {
+		int dec = 0;
+
 		level = btrfs_header_level(b);
 		p->nodes[level] = b;
 
@@ -3025,11 +3027,15 @@ int btrfs_search_old_slot(struct btrfs_root *root, const struct btrfs_key *key,
 		if (ret < 0)
 			goto done;
 
-		if (level != 0) {
-			int dec = 0;
+		if (level == 0) {
+			p->slots[level] = slot;
+			unlock_up(p, level, lowest_unlock, 0, NULL);
+			goto done;
+		}
+
 		if (ret && slot > 0) {
 			dec = 1;
-				slot -= 1;
+			slot--;
 		}
 		p->slots[level] = slot;
 		unlock_up(p, level, lowest_unlock, 0, NULL);
@@ -3040,8 +3046,7 @@ int btrfs_search_old_slot(struct btrfs_root *root, const struct btrfs_key *key,
 			goto done;
 		}
 
-			err = read_block_for_search(root, p, &b, level,
-						    slot, key);
+		err = read_block_for_search(root, p, &b, level, slot, key);
 		if (err == -EAGAIN)
 			goto again;
 		if (err) {
@@ -3061,11 +3066,6 @@ int btrfs_search_old_slot(struct btrfs_root *root, const struct btrfs_key *key,
 		}
 		p->locks[level] = BTRFS_READ_LOCK;
 		p->nodes[level] = b;
-		} else {
-			p->slots[level] = slot;
-			unlock_up(p, level, lowest_unlock, 0, NULL);
-			goto done;
-		}
 	}
 	ret = 1;
 done: